Sara Gutierrez

Multiwell in-gel protein digestion and microscale sample preparation for protein identification by mass spectrometry.

In‐gel peptide digestion has become a widely used technique for characterizing proteins resolved by two‐dimensional gel electrophoresis. Peptides generated from gel pieces are frequently contaminated with detergent and salts. Prior to matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry analysis, these contaminants are removed using micro scale C18 sample preparation columns. In this paper, data are presented to demonstrate the application of a solvent resistant MultiScreen 96‐well plate with a low peptide binding membrane and ZipTip® micropipette based sample preparation. Recoveries of peptides (m/z of 1000 to 5000 Da) derived from standard protein protease digests, were estimated at various stages of the analytical process. An optimized protocol has been established and all the reagents and consumables have been packaged in a ready to use commercial kit. Data will be presented to show the application of this technology package to accelerate the throughput of protein characterization by protease fragmentation.

Development of a Univariate Membrane-Based Mid-Infrared Method for Protein Quantitation and Total Lipid Content Analysis of Biological Samples

Biological samples present a range of complexities from homogeneous purified protein to multicomponent mixtures. Accurate qualification of such samples is paramount to downstream applications. We describe the development of an MIR spectroscopy-based analytical method offering simultaneous protein quantitation (0.25–5 mg/mL) and analysis of total lipid or detergent species, as well as the identification of other biomolecules present in biological samples. The method utilizes a hydrophilic PTFE membrane engineered for presentation of aqueous samples in a dried format compatible with fast infrared analysis. Unlike classical quantification techniques, the reported method is amino acid sequence independent and thus applicable to complex samples of unknown composition. By comparison to existing platforms, this MIR-based method enables direct quantification using minimal sample volume (2 µL); it is well-suited where repeat access and limited sample size are critical parameters. Further, accurate results can be derived without specialized training or knowledge of IR spectroscopy. Overall, the simplified application and analysis system provides a more cost-effective alternative to high-throughput IR systems for research laboratories with minimal throughput demands. In summary, the MIR-based system provides a viable alternative to current protein quantitation methods; it also uniquely offers simultaneous qualification of other components, notably lipids and detergents.

Abstract 3483: A centrifugal ultrafiltration-based method for rapid purification of exosomes from biological samples

Exosomes represent a subset of small particles secreted by many types of cells under both normal and pathological conditions. The release of microvesicles has demonstrated biological relevance; these particles act as mediators of intercellular communication both within the local microenvironment of the release site as well as systemically. Moreover, since exosomes contain RNA (messenger and miRNA) and protein (membrane-bound and cytosolic) from their cells of origin, and given that this content can be influenced by cell state, they also potentially represent a burgeoning target for biomarker discovery. Critical to understanding the physiological significance of these particles is the development of preparative techniques permitting reliable isolation of purified fractions. While numerous methods of exosome purification exist, including ultracentrifugation, immunoaffinity-based isolation using magnetic beads, precipitation, and ultrafiltration, most are plagued by sample limitations or require long and tedious workflows to achieve success. Here we present a rapid alternative method for the selective fractionation of exosomes from biological samples using an ultrafiltration device. Since the method is spin-based and dependent on size exclusion, the device has broad applications with regards to sample volume and/or type. Optimization of the protocol was aided through use of a mid infrared (MIR)-based spectroscopy platform that permits simultaneous monitoring of lysis conditions, protein quantitation, and analysis of total lipid content during exosome fractionation. Given the ultrafiltration device9s capacity for buffer exchange and sample concentration, purified fractions can be easily formatted to meet the requirements of any downstream analysis platform. To demonstrate this, resulting fractions were assayed by numerous techniques including flow cytometry, western blotting, ELISA-based assays, and electron microscopy. Citation Format: Amedeo Cappione, Sara Gutierrez, Masaharu Mabuchi, Janet Smith, Ivona Strug, Timothy Nadler. A centrifugal ultrafiltration-based method for rapid purification of exosomes from biological samples. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3483. doi:10.1158/1538-7445.AM2014-3483

Abstract 4152: New methods for the isolation and analysis of biomarkers from exosomes in cell culture media and bio-fluids.

Microvesicles, such as exosomes, are small particles secreted by many types of cells under both normal and pathological conditions such as cancer. These microparticles contain RNA and protein (both membrane-bound and cytosolic) from their cells of origin and thus represent a burgeoning resource for biomarker identification. While plasma and urine offer convenient, non-invasive access to sufficient sample volumes for screening purposes, major obstacles to this effort include the problematic issues of exosome isolation methods, the presence of over-abundant proteins or interfering cell debris, and the wide dynamic range of protein expression. It is clearly recognized in many fields that the quality of sample preparation ultimately impacts their performance in downstream analyses; this is particularly true where the target in question is a low abundant protein. Here we present an ultrafiltration-based method for the isolation of microvesicles from cell culture media as well as body fluids. To assist in process optimization, we used a novel infrared (IR) based biomolecule detection system to evaluate lysis and extraction conditions and analyze protein and lipid content. This IR system is less influenced by reducing agents and detergents than either BCA or Bradford assays. Following isolation, samples were analyzed using a rapid immunodetection technique, permitting detection of biomarkers more quickly and efficiently than ever before. Citation Format: Sara Gutierrez, Ivona Strug, Amedeo Cappione, Janet L. Smith, Masaharu Mabuchi, Timothy Nadler. New methods for the isolation and analysis of biomarkers from exosomes in cell culture media and bio-fluids. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4152. doi:10.1158/1538-7445.AM2013-4152

Optimierung von Western Blot-Signalen mit Chemilumineszenz

ZusammenfassungWestern Blot zum Nachweis von Proteinen in Zelllysaten ist eine wertvolle Ergänzung zu immunzytochemischen Methoden. Erfolgreiche Western Blots erfordern die Optimierung mehrerer Variablen. Diese Studie zeigt die Optimierung der Chemilumineszenz-Detektion.AbstractUsing Western blotting to detect proteins in a cell lysate is a powerful, complementary approach to immunocytochemistry. Successful Western blotting is dependent on the optimization of multiple variables. In this study, we focused on optimization of chemiluminescence detection